Reinforced cement

Abstract

Cement product reinforced with p-aramid or acrylic fiber coated with certain sulfonyl azides.

We claim: 
     
       1. A fiber-cement product comprising a cement matrix reinforced with fibers selected from the group consisting of p-aramid and acrylic fiber, said fiber being coated with a sulfonyl azide of the formula ##STR6## where X, Y and Z, which may be the same or different, are selected from the group consisting of hydrogen, carboxyl and hydroxyl, with the proviso that at least one but not all of X, Y and Z is hydrogen, said coating being in an amount sufficient to improve adhesion of the fiber to the cement matrix. 
     
     
       2. The product of claim 1 wherein the coated fiber is present in an amount of from 0.5 to 4 weith percent. 
     
     
       3. The product of claim 2 wherein the coated fiber is present at about 1 to 2 weight percent. 
     
     
       4. The product of claim 1 wherein the fiber is coated with from 1 to 2 percent by weight of the sulfonyl azide. 
     
     
       5. The product of claim 1 wherein the sulfonyl azide is p-carboxybenzenesulfonyl azide. 
     
     
       6. The product of claim 1 wherein the sulfonyl azide is m-carboxybenzenesulfonyl azide. 
     
     
       7. The product of claim 1 wherein the sulfonyl azide is p-hydroxybenzenesulfonyl azide.